The present invention relates to Hall effect sensors. In particular, an apparatus for mounting a movable magnet for use in a Hall effect sensor is disclosed.
Hall sensors pick up and convert the magnetic field intensity of a magnet into a useful electrical signal. For example, known quantities such as position, speed, orientation and temperature etc. of an object can be determined by the intensity of the magnetic field sensed by the Hall sensor.
As expected, numerous applications utilizing a Hall effect position sensor have been employed. One such application is a Hall angular position sensor which determines the angular position of an object. Here, a magnet is mounted for rotation about an axis and according to the rotational position of the magnet""s North Pole with respect to the axis, indicates that position of an object.
However, a major problem encountered with Hall angular position sensors is accurately controlling the distance between the magnet and the Hall sensor during rotation. For example, as a change in distance between magnet and the Hall sensor occurs, the intensity of the magnetic field surrounding the sensor is changed. This results in the Hall sensor interpreting the change in the magnetic field intensity being measured as a change in the angular position of the magnet which, of course, relates to the angular position of an object. Accordingly, unwanted change in the positioning of the magnet with respect to the Hall sensor will result in undesired false readings.
Accordingly, there is a need for an improved means for mounting and controlling the position of a magnet in a Hall effect sensor.
In an exemplary embodiment, a plastic bearing is inserted into a steel ring and a magnet is fixedly secured within an inner opening of the bearing. The bearing and its mounting allows the magnet to rotate about an axis without any unwanted movement.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.